Liquid crystal display

ABSTRACT

A liquid crystal display (LCD) including a first substrate and a second substrate. A plurality of gate lines and data lines are formed on the first substrate perpendicular to each other to define a plurality of pixel regions. A thin film transistor is formed for every one pixel. A common electrode is formed on the second substrate. A gate pad, a data pad, and a common electrode pad electrically are connected to each of the gate lines, data lines, and common electrodes respectively. A data on/off pad is formed between adjacent data pads in substantially the same pattern as the data pad for testing a data signal applied to the pixel region. A gate on/off pad is formed between adjacent gate pads in substantially the same pattern as the gate pad for testing a gate signal applied to the pixel region. A common electrode on/off pad is provided for testing a common electrode signal applied to the pixel region. The LCD thereby prevents damage from a rubbing cloth caused by the spacing between the on/off pads, to improve a picture quality.

This application claims the benefit of Korean Patent Application No.2000-84091 filed on Dec. 28, 2000, which is hereby incorporated byreference for all purposes as if fully set forth herein

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display (LCD). andmore particularly, to an LCD which is not affected by a rubbing clothused to form a uniform orientation film.

2. Discussion of the Related Art

FIG. 1 illustrates a plan view of a related art LCD, FIG. 2 illustratesan enlarged view of part “A” in FIG. 1, and FIG. 3 illustrates a sectionof part “B” in FIG. 1, showing sections of pads.

Referring to FIG. 1, the related art LCD 10 is provided with an uppersubstrate 200 having a pixel region A/A defined thereon bonded with alower substrate 100 by a sealing material, and liquid crystal (notshown) sealed between the substrates, As shown in FIG. 2, there are aplurality of pads for contacting a Tape Carrier Package (TCP) at edgesof the lower substrate 100, i.e., data pads (DP), gate pads (GP), anddata on/off pads (DOP, DOFP) and gate on/off pads (GOP, GOFP) fortesting independent patterns between the common electrode, data and gatepads. There is a static electricity preventing circuit (not shown)formed at portions excluding the pixel region A/A on the upper substrate100. Though not shown, there is a common electrode formed either on theupper substrate 200 or the lower substrate 100. In operation, the commonelectrode has a field applied thereto together with a transparent pixelelectrode (or data electrode, not shown) formed in a pixel region of thelower substrate 100 to change an orientation of the liquid crystallayer. There are also common electrode pads and common electrodes on/offpads.

Referring to FIG. 2, all of the common electrode, data and gate pads andthe on/off pads are connected at an outer side of the panel in an “L”line for applying a signal to the pixel region at the same time, andthen the panel is tested. Upon completion of the test, the “L” line isremoved.

Referring to FIG. 3, a gate line 101 is formed on the lower substrate100 of a material such as glass. A gate insulating film 102 is formed onthe lower substrate 100 including the gate line 101. The gate insulatingfilm 102 is etched until a region of the gate line 101 is exposed. Thepads GP, GOP, and GOFP are formed on the etched regions.

Before the upper substrate 200 and the lower substrate 100 are bonded,an orientation film (not shown) is formed on the lower substrate fororientation of the liquid crystal after a Thin Film Transistor (TFT)array is formed for driving the pixel region A/A. The orientation filmis rubbed with a rubbing cloth 300 for forming fixed grooves.

However, referring to FIG. 3, because there are gate on/off pads(GOP/GOFP) between every gate pad GP, the rubbing cloth 300 passes upperparts of the gate on/off pads (GOP/GOFP) initially in the rubbingprocess in the fabrication of the liquid crystal cell. The rubbing cloth300 may be damaged by the spacing between the gate on/off pads(GOP/GOFP) and the environment. Particularly, once the rubbing cloth 300is damaged from the spacing at both ends of the gate on/off pads(GOP/GOFP), the damaged rubbing cloth 300 forms scratches in the pixelregion A/A when the rubbing cloth 300 passes through the pixel regionA/A, which causes blurs to be displayed when the LCD is operated.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a liquid crystaldisplay that substantially obviates one or more of the problems due tolimitations and disadvantages of the related art.

An advantage of the present invention is to provide an LCD, in whichdamage from a rubbing cloth caused by the spacing between on/off pads isprevented thus improving the picture quality.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, the liquidcrystal display includes a first substrate and a second substrate; aplurality of gate lines and data lines formed on the first substrateperpendicular to each other to define a plurality of pixel regions; athin film transistor formed for every one pixel; a common electrode onthe second substrate; a gate pad, a data pad, and a common electrode padelectrically connected to each of the gate lines data lines, and commonelectrodes respectively; a data on/off pad formed between adjacent datapads in substantially the same pattern as the data pad for testing adata signal applied to the pixel region; a gate on/off pad formedbetween adjacent gate pads in substantially the same pattern as the gatepad for testing a gate signal applied to the pixel region; and a commonelectrode on/off pad for testing a common electrode signal applied tothe pixel region.

In another aspect of the present invention, there is provided an LCDincluding a first substrate and a second substrate; gate lines andcommon lines formed on the first substrate; data lines formedperpendicular to gate lines to define a plurality of pixel regions; athin film transistor formed for every one pixel; a common electrode anda data electrode formed in parallel for generating an in-plane fieldbetween the common electrode and the data electrode; a gate pad, a datapad, and a common electrode pad electrically connected to each of thegate lines, data lines, and common lines respectively, a data on/off padformed between adjacent data pads in substantially the same pattern asthe data pad for testing a data signal applied to the pixel region; agate on/off pad formed between adjacent gate pads in substantially thesame pattern as the gate pad for testing a gate signal applied to thepixel region; and a common electrode on/off pad formed between adjacentcommon electrode pads for testing a common electrode signal applied tothe pixel region.

A pitch between the data pad and the data on/off pad may besubstantially identical to the pitch between the data pads.

The gate on/off pad has a pattern substantially identical to the patternof the gate pad, and a pitch between the gate pad and the gate on/offpad is substantially identical to the pitch between the gate pads.

The common electrode on/off pad has a pattern substantially identical tothe pattern of the common electrode pad, and a pitch between the commonelectrode pad and the common electrode on/off pad is substantiallyidentical to the pitch between the common electrode pads.

The thin film transistor includes a gate electrode formed at the sametime as the gate line, a gate insulating film formed on an entiresurface of the substrate including the gate electrode, a semiconductorlayer formed on the gate insulating film, an ohmic contact layer formedon the semiconductor layer, and source and drain electrodes formed onthe ohmic contact layer.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention:

In the drawings:

FIG. 1 illustrates a plan view of a related art LCD;

FIG. 2 illustrates an enlarged view of part “A” in FIG. 1;

FIG. 3 illustrates a section of part “B” in FIG. 1;

FIG. 4 illustrates a plan view of an LCD in accordance with anembodiment of the present invention;

FIG. 5 illustrates an enlarged view of part “C” in FIG. 4; and,

FIGS. 6A and 6B illustrate sections of a gate pad part and a data padpart in FIG. 4, respectively.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to the LCD and the in-planeswitching mode LCD of an embodiment of the present invention, examplesof which are illustrated in the accompanying drawings.

FIG. 4 illustrates a plan view of an LCD in accordance with anembodiment of the present invention, FIG. 5 illustrates an enlarged viewof part “C” in FIG. 4, and FIGS. 6A and 6B illustrate sections of thegate pad part and the data pad part in FIG. 4, respectively.

Referring to FIG. 4, the LCD 10 in accordance with an embodiment of thepresent invention includes an upper substrate 200 having a pixel regionA/A defined thereon bonded with a lower substrate 100 by a sealingmaterial, and liquid crystal (not shown) sealed between the substrates.There are a plurality of pads for contacting a TCP at edges of the lowersubstrate 100, i.e., data pads DP, gate pads GP, and testing data on/offpads DOP/DOFP and testing gate on/off pads GOP/GOFP between the datapads DP and the gate pads GP respectively formed such that at least oneof the testing data on/off pads DOP/DOFP and the testing gate on/offpads GOP/GOFP has substantially the same pattern with the data pads DPand gate pads GP, respectively. There is a static electricity protectingcircuit (not shown) at parts excluding the pixel region (A/A) on theupper substrate 200. Though not shown, there is a common electrodeformed either on the upper substrate 200 or the lower substrate 100 forhaving a field applied thereto together with a transparent pixelelectrode (or data electrode, not shown) formed in a pixel region of thelower substrate 100, to change an orientation of the liquid crystallayer, common electrode pads, and common electrodes on/off pads.

The common electrode on/off pad may also be formed in substantially thesame pattern as the common electrode pad.

The sections of pads will now be described in more detail with referenceto FIG. 5. All the on/off pads may be formed substantially identical tothe common electrode, data and gate pads, with a pitch between the datapads DP and the on/off pads (DOP and DOFP) formed substantiallyidentical to a pitch between the gate pads. Moreover, though not shown,a pitch between the gate pad GP and the gate on/off pad GOP and GOFP maybe formed substantially identical to the pitch between the gate pads,and the pitch between the common electrode pad and the common electrodeon/off pad may be formed substantially identical to the pitch betweenthe common electrode pads. The gate on/off pad GOP/GOFP, the data on/offpad DOP/DOFP, and the common electrode on/off pad may be form of atransparent conductive material, such as indium tin oxide (ITO).

Referring to FIG. 2, all the common electrode, data and gate pads andthe on/off pads are connected at an outer circumference of the panel inan “L” line for applying a signal to the panel, i.e., to the pixelregion at the same time, for testing the panel. Upon completion of thetesting, the “L” line is removed. A data line connected to an evennumbered pad may be connected to an even numbered on/off pad, and a dataline connected to an odd numbered pad may be connected to an oddnumbered on/off pad.

After a system of on/off pads is formed and, before the upper substrate200 and the lower substrate 100 are bonded as shown in FIG. 4, anorientation film (not shown) is formed on the lower substrate fororientation of the liquid crystal after a TFT array process is carriedout for driving the pixel region A/A, and the orientation film is rubbedwith rubbing cloth 300 for forming fixed grooves.

Since an appropriate number of the on/off pads of the same form as thecommon electrode, data and gate pads are provided, and the on/off padsare formed to have an substantially identical spacing as the commonelectrode, data and gate pads, for minimizing the spacing between thecommon electrode, data and gate pads, damage to the rubbing cloth isminimized.

A TFT array process and an electrode pad forming process of the LCD 10having the pixel region A/A and the pad region excluding the pixelregion will be explained with reference to FIGS. 6A and 6B.

A gate line 101 of a metal is formed on a transparent substrate 100, anda gate insulating film 102 is formed on the gate line 101. In thisinstance, the gate line 101 is formed at the same time as a gateelectrode in a pixel region A/A, and a gate insulating film 102 is alsoformed on an entire surface including the gate line and the gateelectrode as one unit. Next, after a protection film 103 is formed onthe gate insulating film 102, the gate insulating film 102 and theprotection film 103 are etched, to open lines for connection with anexternal driving circuit. Gate pads GP of a transparent conductive filmare formed to connect with the gate line 101 through the opened part,when the pixel electrode is formed in the pixel region. The data line201 is formed on the gate insulating film 102 at a location of a thinfilm transistor in the pixel region, together the source and drainelectrodes in the pixel region as one unit after a semiconductor layerand an ohmic contact layer are formed. Next, after the protection film103 is stacked, the protection film 103 is etched as required to openthe line. Then, a data pad DP is formed of a transparent material to bein contact with the data line 201 through the opened part, when thepixel electrode in the pixel region is formed at the same time. Thoughnot shown, a gate on/off pad GOP/GOFP and a data on/off pad DOP/DOFP insubstantially the same pattern as the gate pad GP and the data pad DPare formed, together with the gate pad GP and the data pad DP.

As has been explained, the LCD of the present invention has thefollowing advantages.

Though rubbing on an LCD panel having on/off pads of independentpatterns causes damage to the rubbing cloth from outer metal parts ofthe independent patterns which forms blurs on the panel, the change ofthe on/off pads of independent patterns into substantially identicalforms as the electrode pads does not damage the rubbing cloth andprevents blurs on the panel, thereby improving the picture quality, forexample, in the case of a current in-plane switching mode LCD or atwisted nematic (TN) LCD.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the LCD of the presentinvention without departing from the spirit or scope of the invention.Thus, it is intended that the present invention cover the modificationsand variations of this invention provided they come within the scope ofthe appended claims and equivalents.

1. A liquid crystal display (LCD) comprising: a first substrate and asecond substrate; a plurality of gate lines and data lines formed on thefirst substrate perpendicular to each other to define a plurality ofpixel regions; a thin film transistor formed for every one pixel; acommon electrode on the second substrate; a gate pad, a data pad, and acommon electrode pad electrically connected to each of the gate lines,data lines, and common electrodes, respectively; a data on/off padbetween adjacent data pads in substantially the same pattern as the datapad for testing a data signal applied to the pixel region; a gate on/offpad between adjacent gate pads in substantially the same pattern as thegate pad for testing a gate signal applied to the pixel region; and, acommon electrode on/off pad for testing a common electrode signalapplied to the pixel region.
 2. An LCD as claimed in claim 1, wherein apitch between the data pad and the data on/off pad is substantiallyidentical to the pitch between the data pads.
 3. An LCD as claimed inclaim 1, wherein the gate on/off pad has a pattern substantiallyidentical to the pattern of the gate pad.
 4. An LCD as claimed in claim3, wherein a pitch between the gate pad and the gate on/off pad issubstantially identical to the pitch between the gate pads.
 5. An LCD asclaimed in claim 1, wherein each of the gate on/off pad, the data on/offpad, and the common electrode on/off pad include a transparentconductive material.
 6. An LCD as claimed in claim 5, wherein thetransparent conductive material includes indium tin oxide.
 7. An LCD asclaimed in claim 1, wherein the thin film transistor includes; a gateelectrode connected with a gate line; a gate insulating film on anentire surface of the substrate inclusive of the gate electrode; asemiconductor layer on the gate insulating film; an ohmic contact layeron the semiconductor layer; and source and drain electrodes on the ohmiccontact layer.
 8. A liquid crystal display (LCD) comprising: a firstsubstrate and a second substrate; gate lines and common lines formed onthe first substrate; data lines formed perpendicular to gate lines todefine a plurality of pixel regions; a thin film transistor formed forevery one pixel; a common electrode and a data electrode in parallel,for generating an in-plane field between the common electrode and thedata electrode; a gate pad, a data pad, and a common electrode padelectrically connected to each of the gate lines, data lines, and commonlines, respectively; a data on/off pad between adjacent data pads insubstantially the same pattern as the data pad; a gate on/off padbetween adjacent gate pads in substantially the same pattern as the gatepad; and, a common electrode on/off pad between adjacent commonelectrode pads for testing a common electrode signal applied to thepixel region.
 9. An LCD as claimed in claim 8, wherein a pitch betweenthe data pad and the data on/off pad is substantially identical to thepitch between the data pads.
 10. An LCD as claimed in claim 8, whereinthe gate on/off pad has a pattern substantially identical to the patternof the gate pad.
 11. An LCD as claimed in claim 10, wherein a pitchbetween the gate pad and the gate on/off pad is substantially identicalto the pitch between the gate pads.
 12. An LCD as claimed in claim 8,wherein the common electrode on/off pad has a pattern substantiallyidentical to the pattern of the common electrode pad.
 13. An LCD asclaimed in claim 12, wherein a pitch between the common electrode padand the common electrode on/off pad is substantially identical to thepitch between the common electrode pads.
 14. An LCD as claimed in claim8, wherein each of the gate on/off pad, the data on/off pad, and thecommon electrode on/off pad include a transparent conductive material.15. An LCD as claimed in claim 14, wherein the transparent conductivematerial includes indium tin oxide.
 16. An LCD as claimed in claim 8,wherein the thin film transistor includes; a gate electrode connectedwith a gate line; a gate insulating film on an entire surface of thesubstrate including the gate electrode; a semiconductor layer on thegate insulating film; an ohmic contact layer on the semiconductor layer;and source and drain electrodes on the ohmic contact layer.
 17. A liquidcrystal device (LCD) comprising: an upper substrate having a pixelregion defined thereon; a lower substrate bonded with the uppersubstrate by a sealing material and having a plurality of pads providedat edges of the lower substrate, the plurality of pads including datapads, gate pads, testing data on/off pads and testing gate on off/pads;wherein at least one of the testing data on/off pads and the testinggate on/off pads has substantially the same pattern as the data pads andthe gate pads, respectively; wherein at least one testing data on/off adis between adjacent data on/off pads; wherein at least one testing gateon/off pad is between adjacent sate on/off pads; and a liquid crystalprovided between the substrates.
 18. An LCD as claimed in claim 17,wherein a pitch between the data pad and the data on/off pad issubstantially identical to the pitch between the data pads.
 19. An LCDas claimed in claim 17, wherein the gate on/off pad has a patternsubstantially identical to the pattern of the gate pad.
 20. An LCD asclaimed in claim 17, wherein a pitch between the gate pad and the gateon/off pad is substantially identical to the pitch between the gatepads.
 21. An LCD as claimed in claim 17, wherein each of the gate on/offpad and the data on/off pad include a transparent conductive material.22. An LCD as claimed in claim 21, wherein the transparent conductivematerial includes indium tin oxide.
 23. An LCD as claimed in claim 17,wherein all of the common electrode, data and gate pads and the on/offpads are connected at an outer circumference of the LCD in an L line forapplying a signal to the pixel region at substantially the same time.24. An LCD as claimed in claim 17, wherein a data line is connected toan even numbered pad and an even numbered on/off pad.
 25. An LCD asclaimed in claim 17, wherein a data line is connected to an odd numberedpad and an odd numbered on/off pad.
 26. An LCD as claimed in claim 17,further comprising an orientation film provided on the lower substrate.27. A method of manufacturing a liquid crystal device (LCD) comprising:forming a gate line made of metal on a transparent substrate; forming agate electrode at the same time as the gate line; forming a gateinsulating film on the gate line; forming a protection film on the gateinsulating film; etching the gate insulating film and the protectionfilm to form first open parts; forming gate pads made of a transparentconductive material to connect with the gate line through the first openparts; forming a pixel electrode at the same time as the gate pads;forming a data line on the gate insulating film; forming source anddrain electrodes at the same time as the data line; etching theprotection film to form second open parts; forming data pads made oftransparent conductive material to connect with the data line throughthe second open parts; and forming gate on/off pads and data on/off padshaving substantially the same pattern as the gate pads and providedbetween gate pads.
 28. The method as in claim 27, wherein the data lineand source and drain electrodes are formed after a semiconductor layerand an ohmic contact layer are formed.
 29. The method as in claim 27,wherein the orientation film is rubbed with a rubbing cloth to formgrooves in the film.